Film merchandise bags are manufactured from petroleum products and various organic material substitutes, all of which are increasingly expensive resources. It is difficult to produce such bags in formulations that are easily biodegradable. As the quantity of merchandise used daily is enormous, the production and disposal of these bags has a significant effect on the environment. For these reasons, it is desirable to produce merchandise bags that use a minimum of thermoplastic or plastic-substitute material. Some of the materials presently in use or contemplated for merchandise bags include high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, polylactic acid (PLA), poly-3-hydroxybutyrate (PHB), bio-derived polyethylene including materials produced from corn, sugar cane, tapioca, and potatoes and genetically modified bioplastics.
One way to minimize the use of these materials is to use a thinner gauge film in the manufacture of the bags. As merchandise bags used in the grocery and supermarket environments are often used to carry heavy loads of canned goods and other items that may have sharp edges, these merchandise bags need to have a certain minimum resistance to piercing and tearing under such conditions. Use of thinner film in bag construction can result in torn or burst bags, a situation that is not acceptable to retail stores and their customers.
The typical merchandise bag used in the grocery and supermarket setting is the T-Shirt style bag. This bag has a U-shaped open mouth at the upper end with a pair of strap handles extending upwardly from the mouth. In order to make the handles stronger, side gussets are typically formed prior to sealing the upper and lower edges of the bag and forming the bag mouth. This provides four layers of film material in the bag handles compared with two layers for the front and back walls of the bag. High stress areas in merchandise bags include the bag handles and the bottom of the bag, both points at which maximum tensile stress is experienced. In the present invention, several techniques may be employed to increase strength in these critical areas when using a thinner gauge film material in bag construction. These techniques include thickening one or more of the bag walls in specified locations and multiplying the layers of film material in the bag handles. Various inventions have been developed to increase strength of plastic bags.
U.S. Pat. No. 5,338,118, issued to DeMatteis is directed to a plastic bag having an aperture serving as a handle which has a contour of peaks and valleys. The peaks fold in an accordion-like manner when pressed by fingers to cushion the fingers. The area surrounding the bag handle opening is formed with a thicker plastic extrusion while the balance of the bag is of a standard thickness, lending strength to the handle area of the bag.
U.S. Pat. No. 7,223,016, issued to Bell illustrates a collapsed bag of unitary construction made of supple polymeric material, having first and second opposed contiguous flat sidewalls joined at edges and at the bottom but free or with user-releasable weakening at upper edges. The upper edges define a bag mouth. Appropriately situated graspable points at or near bag edges allow the sidewalls to be tensioned or snapped in opposing directions thereby causing the interlayer cling, to which supple polymeric bags are renownedly susceptible, to be readily disrupted for the full distance of contact between the tensioning points and thus for virtually the entirety of the bag mouth to be opened. Performance of this bag opening feature can be improved in a square-topped bag by thickening the plastic material in the area of the bag mouth.
U.S. Pat. No. 6,565,794, issued to Fraser discloses a tie bag having improved tie features provided by increasing the thickness of the tie features as compared to the bag thickness.
It is an objective of the present invention to provide a film merchandise bag having size and strength characteristics of a standard bag that can be manufactured using substantially less film material. It is another objective to provide such a bag manufactured from a thinner gauge film. It is a further objective of the invention to provide a bag that will have a more uniform thickness across the bag width, to aid in storage and packing of bag stacks. It is still a further objective to provide a bag that is resistant to failure along the bottom seam. It is yet a further objective to provide bag designs that are adaptable to use with or without dispensing racks. Finally, it is an objective of the present invention to provide durable bags that are more easily biodegraded and are economical to produce.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.